The traditional method for inoculating animals is to use a needle and syringe. This process is time-consuming and labor-intensive, because the animals must be herded and sometimes separated or restrained. Also, the needle and syringe method is stressful for both the user and the animal. Further, the protection level achieved by the needle and syringe method is sometimes very low. Often, the user inadvertently pushes the syringe's plunger before the needle is completely within the animal or as it is being withdrawn from the animal. As a result, there are potential problems of cross-contamination and inaccurate dosage. In addition, there is a danger of contamination when a first contaminated animal is administered with the inoculating device, and the same device is then used on successive animals.
A convenient, inexpensive and safe way to administer biologicals and pharmaceuticals to animals is to utilize projectiles, each projectile containing a separate dose of a biologically active material for inoculation. Each projectile is fired from a gun at some distance from the animal. The projectile or biodegradable "bullet" is implanted into the animal's muscle, where it dissolves and is carried through the animal's system during the next hours.
The biodegradable projectiles are advantageous for several reasons. Each one contains the necessary, accurate dosage depending upon the animal and the inoculation project. Each projectile or bullet can be filled with mixtures of multiple vaccines, bacterins or pharmacuetical products. This eliminates the need for mixing and measuring out in the field. The bullets can also be stored for an indefinite period of time, especially if they are refrigerated. They are convenient to use, store, handle and ship. The biologically active material within the projectiles is a freeze-dried product. In this form, contamination and loss of potency are prevented. Such projectiles are described in patents assigned to the assignee of this application and are identifed as Drake and Paul, U.S. Pat. No. 3,948,263, issued Apr. 6, 1976; and Krogseng and Paul, U.S. Pat. No. 3,982,536, issued Apr. 28, 1976.
To store these bullets or projectiles, a clip containing a plurality of cavities of chambers may be used, each chamber containing one projectile. This type of clip features a rupturable seal on each open end of each chamber, to protect the contents from impurities, providing a hygienically packaged projectile. Another feature of this type of clip is an indexing means which automatically advances the clip so that successive chambers, each containing a projectile, are automatically aligned with the bore of the gun. Each time the gun is fired and cocked, the clip automatically advances and chambers a new projectile. Typically, this type of clip contains ten chambers which hold ten projectiles. This clip is described in a patent application assigned to the assignee of this application, and is identifed as Fischer and Gould, U.S. Pat. No. 4,004,565, issued Jan. 25, 1977. The indexing mechanism associated with the gun is decribed in patent application identified as Fischer, U.S. Pat. No. 4,004,566, issued Jan. 25, 1977.
However, a user of the above type of clip is often unaware when the clip becomes empty and contains no more projectiles. There is no physical indication to tell the user that he is firing nothing but air. The gun continues to fire, and the bolt of the gun continues to project through the last empty chamber, until the user finally realizes that there is no longer firing any projectiles. The only way to prevent this situation is to count each time the gun is fired, a practice which is often inconvenient and ineffective. When the user discovers that the clip is empty, he often does not know how many animals have been inoculated and how many have not. The animals then have to be individually sorted out, or the animals who escaped inoculation are simply left without the biological or pharmacuetical product. As a result, there is a potential for a cross contamination by the animals which have not been inoculated.
The present invention solves this problem associated with currently available clips, as well as many problems associated with the traditional needle and syringe method.